1. Field of the Invention
The present invention relates to the field of computer graphics and, in particular, to a circular scratch shader.
2. Description of the Related Art
Shiny surfaces covered by fine multi-directional scratches can give the appearance of concentric circles aligned around an isotropic specular highlight. An example of such a surface is the metallic paint surface of a car. Rending this effect has proven to be quite challenging.
One prior attempt to render this effect involves using extremely high-resolution multi-directional textures. However, this technique is computationally expensive, especially for large surfaces or intricate scenes. Another prior approach involves modulating a noise texture by circular patterns. This approach, however, does not provide realistic or pleasing results.
As the foregoing illustrates, there is a need in the art for an improved technique that addresses the limitations of current approaches set forth above.